It is sometimes desirable to stop fluid flow through a pipeline without the assistance of a valve. For example, a section of pipeline may not be controlled by an upstream valve that will allow fluid flow to be shut off during pipeline repairs. Alternatively, the pipeline may include a valve, but that valve may be broken or otherwise not fully functioning. Accordingly, plugging may be used to temporarily shut off the fluid flow such that needed repairs or other servicing operations can be made to a section of pipeline. In one type of plugging operation, two halves of a tapping sleeve are placed around a pipe at a point along the pipeline where fluid flow is to be shut off. The two halves of the tapping sleeve are typically bolted together. The upper half of the sleeve supports a branch assembly to which a temporary valve is attached. An operator then extends a tapping machine through the temporary valve and the branch assembly and taps an aperture into the wall of the underlying pipe. The temporary valve is used to prevent fluid escape after the tapping machine is removed. Next, a plugging machine is used to extend a plug through the temporary valve, the branch assembly, and the aperture in the pipe wall. Once the plug is in place within the inner walls of the pipe, the fluid flow is stopped and repairs or other service work can be performed downstream of the plug. When not in use for tapping and plugging operations, a push plug with a seal is inserted into the branch to provide a seal of the opening in the branch.